1. Field of the Invention
The present invention relates to a vibration-driven motor, and more particularly to a vibration-driven motor of a type in which an elastic member in which a travelling wave is formed is press-contacted to a rail-shaped stator to move the elastic member along the rail-shaped stator.
2. Related Background Art
A vibration-driven motor having construction as shown in FIG. 9 or 10 has been known in the art.
Numeral 1 denotes an oval elastic member having a comb-shaped projections 1a on a sliding plane. A known piezo-electric element 2 for generating a travelling vibration wave in the elastic member 1 in accordance with an electrical signal applied thereto is joined to an upper surface of the elastic member 1.
Numeral 8 denotes a rail-shaped stator which frictionally contacts to the elastic member 1. It is press-contacted to the elastic member 1 through a vibration insulation material 5 (for example, felt) by a pressure spring 3.
Numeral 6 denotes a comb-shaped stopper. A comb portion 6a thereof (see FIG. 10) is fitted into a slit formed by the projection 1a in a portion of the elastic member 1 which does not contact the rail-shaped stator 8 so that the comb portion 6a supports the elastic member 1 through a felt 7 disposed at the bottom of the slit.
The oval elastic member 1 (see FIG.10) is supported by a mount 4 through the pressure spring 3, and the mount is supported by a guide member 9 which inhibits displacement other than in a B.sub.Y direction (see FIG. 10) which is a predetermined direction of movement.
When a travelling vibration wave is generated in the elastic member 1 in a known method, the elastic member 1 moves on the rail-shaped stator 8 by a frictional force between the rail-shaped stator 8 and the elastic member 1. As a result, the mount 4 and other members (3, 5, 6, 7) also move along the guide member 9 in the B.sub.Y direction. A frictional driving force generated thereby acts on a portion of the elastic member 1. Since that portion is offset from the support point, a moment is applied to the elastic member 1 to shift the elastic member 1 in the B.sub.X and B.sub.Y directions.
The comb portion 6a of the stopper 6 is fitted into the slit of the elastic member 1 formed by the projection 1a as shown in FIG.10. It restricts the displacement of the elastic member 1 to the B.sub.Y direction and supports the weight of the elastic member 1 through the felt 7. The binding members 6b and 6c restrict displacement in the B.sub.X direction, and the binding member 6d restrict displacement of the elastic member 1 on the pressurizing side in the B.sub.Y direction. In association with binding members 6a to 6d, the elastic member 1 is smoothly and linearly moved with the mount 4 without backlash.
In the prior art construction, however, since the elastic member 1 is not fixed to the mount 4, the support member 6 and the elastic member 1 are disjoined piece by piece when the pressure between the rail-shaped stator 8 and the elastic member 1 is released. In other words, it is difficult to assemble them as shown in FIG. 9. Further, since the pressure between the elastic member 1 and the rail-shaped stator 8 is applied by the pressure spring 3 through the felt 5, on the piezo-electric element 2 spaced from a neutral plane of the elastic member 1, a pressure loss is large.